Fire safety and fire protection objectives require that buildings and parts of buildings do not collapse during a fire. This requires that the load-carrying capacity is maintained to a minimum acceptable level during a fire. This chapter briefly describes the historical background and state of the art of fire resistance and its determination for timber members through testing or calculations. The thermal and mechanical principles that underpin structural behaviour of wood at elevated temperatures are explained in the context of explicit calculation methods that enable explicit evaluation of the structural capacity beyond fire resistance, which is a formalised and codified assessment of structural elements against a standard fire. The importance of connections to the overall structure in fire is explained along with suitable design considerations. Ultimately, knowledge gaps with respect to novel and more complex engineered timber products for taller timber buildings are highlighted alongside potential limitations of established design parameters.